The largest U.S.-based companies added $206 billion to their stockpiles of offshore profits last year, parking earnings in low-tax countries until Congress gives them a reason not to.

The multinational companies have accumulated $1.95 trillion outside the U.S., up 11.8 percent from a year earlier, according to securities filings from 307 corporations reviewed by Bloomberg News. Three U.S.-based companies — Microsoft Corp. (MSFT), Apple Inc. and International Business Machines Corp. — added $37.5 billion, or 18.2 percent of the total increase.

“The loopholes in our tax code right now give such a big reward to companies that use gimmicks to make it look like they earn their profits offshore,” said Dan Smith, a tax and budget advocate at the U.S. Public Interest Research Group, which seeks to counteract corporate influence.

Even as governments around the world cut tax rates and try to keep corporations from shifting profits to tax havens, the U.S. Congress remains paralyzed in its efforts. The response of U.S.-based companies over the past few years has been consistent: book profits offshore and leave them there.